Technical Abstract:
White lupin (Lupinus albus) shows numerous adaptations to phosphate deficiency and has been used as a model plant for studying phosphate (P) acquisition in higher plants. Induction of proteoid root (cluster root) formation by phosphate deficiency is a further indication that plants respond to nutrient status by modifying root architecture to facilitate nutrient uptake. To understand the molecular mechanisms of plant responses to P, we focused on genes that are preferentially expressed in plant roots and that respond to changes in phosphate status. Here we report the isolation and characterization of a root-specific MYB-like gene, LaMYB1, whose expression is significantly affected in roots by exogenously supplied phosphate. Protein sequence alignments indicated that the LaMYB1 belongs to the R2R3 group of MYB gene family. Sequencing of a genomic clone revealed that the LaMYB1 gene coding region is interrupted by two introns of 150 bp and 113 bp, respectively. The putative promoter region of gene LaMYB1 has been sequenced and will be used for reporter gene assays. The modulation of gene LaMYB1 expression by P sufficiency and P deficiency suggests that LaMYB1 may be a transcription factor involved in sensing/signaling phosphate status and affecting expression of a set of downstream genes in white lupin.